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                  <p class="p_Heading1"><span class="f_Heading1">Use Case Group</span></p>



  
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                <p class="p_BodyText"><span class="f_BodyText" style="font-style: italic;">Use Case</span><span class="f_BodyText"> elements are used to build <a href="usecasediagram.htm">Use Case models</a>. These describe the functionality of the system to be built, the requirements, the constraints and how the user interacts with the system. Often Sequence diagrams are associated with Use Cases to capture work flow and system behavior.</span></p>
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<td valign="top" width="695" style="width:695px;"><p class="p_BodyText"><span class="f_BodyText">The </span><span class="f_UIControl">Use Case</span><span class="f_BodyText"> group is used to model the system functionality from the perspective of a system user. The user is called an </span><span class="f_BodyText" style="font-style: italic;">Actor</span><span class="f_BodyText"> and is drawn as a stick figure, although the user could be another computer system or similar. A </span><span class="f_BodyText" style="font-style: italic;">Use Case</span><span class="f_BodyText"> is a discrete piece of functionality the system provides that enables the user to perform some piece of work or something of value using the system.</span></p>
<p class="p_BodyText"><span class="f_BodyText">Examples of Use Cases are:</span><span class="f_BodyText" style="font-style: italic;"> login, open account, transfer funds, check balance</span><span class="f_BodyText"> and </span><span class="f_BodyText" style="font-style: italic;">logout</span><span class="f_BodyText">; each of these implies some purposeful and discrete functionality the system is to provide to a user.</span></p>
<p class="p_BodyText"><span class="f_BodyText">The connectors available include: </span><span class="f_BodyText" style="font-style: italic;">associate</span><span class="f_BodyText"> (an actor uses a Use Case), </span><span class="f_BodyText" style="font-style: italic;">extend</span><span class="f_BodyText"> (one Use Case can extend another), </span><span class="f_BodyText" style="font-style: italic;">include</span><span class="f_BodyText"> (one Use Case can include another) and </span><span class="f_BodyText" style="font-style: italic;">realize</span><span class="f_BodyText"> (this Use Case might realize some business requirement).</span></p>
<p class="p_BodyText"><span class="f_BodyText">To add an element to the current diagram, click on the required icon and drag it into position on the diagram. Set an element name and other properties as prompted.</span></p>
<p class="p_BodyText"><span class="f_BodyText">To add a relationship, click on the required icon, then click on the start element in the diagram and drag to the end element.</span></p>
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<td valign="bottom" bgcolor="#efeff7" style="background-color:#efeff7;"><p class="p_TiporNote" style="border-top: none; border-right: none; border-left: none;"><span class="f_TiporNote">Note:</span></p>
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<td bgcolor="#f7f7ff" style="background-color:#f7f7ff;"><p class="p_TiporNoteText"><span class="f_TiporNoteText" style="font-style: italic;">Invokes</span><span class="f_TiporNoteText"> and </span><span class="f_TiporNoteText" style="font-style: italic;">Precedes</span><span class="f_TiporNoteText"> relationships are defined by the Open Modeling Language (OML). They are stereotyped Dependency relationships; Invokes indicates that Use Case A, at some point, causes Use Case B to happen, whilst Precedes indicates that Use Case C must complete before Use Case D can begin.</span></p>
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<p class="p_BodyText"><span class="f_BodyText">&nbsp;</span></p>
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